Composite sheet



June 8,1926. 1,588,243

H. S. LEWIS COMPOS ITE SHEET Filed April 16. 1923 Q-kukev 'R N ATO NEZYSPatented June 8, 1926.

UNITED STATES HARRY S. LEWIS, OF BEAVER FALLS, NEW YORK.

COMPOSITE SHEET.

Application filed April 16, 1923. Serial No. 632,531.

This invention relates to centain improvements in a composite sheet,capable of use for various purposes, but peculiarly designed and adaptedfor use as wall board.

The manufacture of wall board, as practiced today, consists of buildingup by the use of suitable adhesive, two or more plies of so-called woodpulp board manufactured from either ground wood pulp or from socalledpaper stock board manufactured from waste papers, each ply being usuallyfrom .030 to .055 of an inch in thickness according to the number ofplies desired for a certain desired thickness of the finished product,such product being usually from to ,4; of an inch thick.

Some grades of wall board are at present made entirely of boardmanufactured from ground. wood pulp made from 'soft wood, such asspruce,,balsam, hemlock, ineand poplar wood, while other manu acturers,

to reduce the cost of production, use in the finished product centerplies of board manufactured from old paper stock which board commandsmuch lower price in the market than that manufactured direct fromv the around wood pulp, but the combined or finished board fre uently'lacks therigidity and strength of t e wall board manufactured from all freshground wood'pulp.

Rigidity is a characteristic of considerable importance in connectionwith the pro-' duct known as wall board, and I have experimentedextensively in an effort to produce a wall board of greater rigidity andstrength as compared with the commercial wall board made today, Myexperiments have led to. a development quite remote from the present daymanufacture of wall board and to the use of material heretoforeconsidered impractical for that pur ose, viz: the use of ground woodmade rom hard wood, such as beech, birch, maple, elm, chestnut, oak,etc. adequately steamed or boiled preliminary to grinding.

The pulp board of this invention is more rigid than ordinary pulp boardof the same number of plies formed of wood pulp manufactured from softwood or so-called paper stock board manufactured from waste papers, andby reason of the solidity and non-porous nature of the surface, it isbetter adapted for certain uses, particularly where finishing'materialis to be applied to the board. Further, the board is characterhandlingon apaper machine'without ad-' mixture of other stock and commercially'useless for the purpose at hand. I have found, however, that if hardwood is properly and adequately steamed or boiled prior to grinding inthe usual manner of grinding wood pulp, that a wood pulp is producedwhich when manufactured into board has the desired characteristic .ofunusual rigidity and strength.

Therefore, in the process of manufacturing wood pulp from hard wood, thewood is subjected to steaming and boiling prelimi-. nary to grinding andpurely as illustrative of a=-suitable operation of that character thewood in a closed chamber. may be subjected to the action of steam underpressure as, for instance, fifty pounds for a period of eighteen hours.It is then ground and formed into single ply in the usual manner oftreating soft wood pulp.

J The com osite wall board is then built .up of any esired number ofplies or laminations of ordinary pulp board such as board manufacturedfrom soft wood or from paper stock. These center plies may be anyordinary desired board. An outer or facing ply is secured upon each sideof the composite structure already formed.

Each of these facing plies consists of or comprises wood pulpmanufactured from ground cooked hard wood.

I, therefore, claim as new and original,

the manufacture of a composite or built-up board suitable for wall boardor for other purposes the center plies of which may be ordinary softwood" pulp board or paper stock board, while the outer or facing pliesconsist of and comprise either wholly or in part, wood ulp manufacturedfrom ground cooked hard wood.

' of board which are afterward laminated or built up into the plural plyor finished wall board, a single ply sheet orweb is built up on theso-called board machine in two or more layers by the use of two or morecylinders, these layers adhering to each other because of the pressureexerted upon the web while it is still in a moist state. In this mannerit is possible to manufacture a web or sheet of single ply board for useas the two outside plies, sheets or laminations for the finishedcomposite board, with as many cylinders as desired running on the pulpproduced from steamed or boiled hard wood and with one or more cylindersrunning on pulp of other character, such as that produced from softWoods, so that the finished single ply sheet may consist of any desirednumber of layers formed from wood pulp manufactured from soft wood orother material and the finished single ply sheet may, therefore, haveany desired shade or color upon either or both sides while the center oreither or both sides may consist entirely of board containing anypercentage desired of the pulp made from the steamed or boiled hard woodof characteristic brown color.

In the drawings I have illustrated various forms that my invention maytake.

Figure 1 is" a sectional View through a board of my invention.

Figure 2 is a sectional view through a board of a somewhat modifiedconstruction.

Figure 3 is a sectional view of a further modified form of board.

In Figure 1 I have illustrated a board consisting of five plies,laminations or sheets No. 1, 2, 3, 4 and 5 respectively. The plies -2, 3and 1 may be the ordinary wood pulp board of commerce, such as boardmanufactured from soft Wood pulp or from waste papers, while the outeror facing plies 1- and --5 consist of or comprise a substantialpercentage of wood pulp' manufactured from ground cooked hard wood. Theintermediate or center plies afford the desired bulk andnon-conductivity to the board, while the outer plies produce unusualrigidity with a relatively'hard nonporous surface for exposure or forthe reception of a finishing material.

The structure of Figure 2 differs in that the outer or facing plies 6and -7 each consist of a single ply which embodies an outer layer orseries of layers 8 formed of wood pulp made from soft wood or othermaterial such as waste paper and the inner layer or series of layers 9-are formed of or embody a substantial percentage of wood pulpmanufactured from ground steamed or boiled hard wood. These acing plies-6 and -7- can be manufactured on the usual and well known board thelatyers 8 are formed of wood pulp manu actured from soft wood, while thelayer or layers -9- are manufactured from ground cooked hard wood.

Figure 3 embodiesthe same elements as Figure 2. The central plies -2, 3-and --4- in each of Figures 2 and 3 corresponding to the plies 2-, 3-and -4 in Figure 1, while the outer or facing plies of Figures 2 and 3are in construction exactly the same. They are assembled with thecentral plies 2, 3 and 4 in a reverse manner, that is, the layer -9 isplaced at the outer side instead of the inner side adjacent the centralplies -2- and 4. With this construction some rigidity is sacrificed ascompared with the structure of Figure 1, but the solidity and non porousnature of the exposed surface is retained. The formation of plies 6 and7 in the manner illustrated permits, as shown in Figures 2 and 4 oftheir assemblage with the ordinary plies 2-, 3

- and 4-- in either the manner shown in Figure 2 or the manner shown inFigure 3, dependent upon the particular characteristics required for aparticular use. The plies constituting the composite board may be unitedin any suitable manner as by an adhesive or cement, such as silicate ofsoda, to constitute a relatively rigid unitary sheet.

It will be understood that a percentage of soft wood pulp or paper stockpulp or other material may be added to the hard wood pulp during thebeating or mixing process with perhaps somewhat less advantageousresults and that the composite board may be formed of any desired numberof plies or laminations and that such laminations, plies or sheets maybe secured together in any suitable manner and that each sheet mayconsist of, or comprise any desired percentage of wood pulp manufacturedfrom hard wood cooked by'the steaming or boiling process, and thatvarious modifications may be made in the details of the process and theproduct all without departing from the invention asset forth in theappended claims.

I claim: 4

l. A laminated board, the facing plies of which comprise wood pulpmanufactured one from ground cooked hard wood and the center plies ofwhich comprise pulp manufactured from other material.

2. A laminated board, the facing plies of which consist of wood pulpmanufactured from ground, cooked hard wood and the center plies of whichconsist of pulp manufactured from other material.

3. A laminated board, the facing lies of which comprise wood pulp manuactured from ground cooked hard wood and the center plies of whichcomprise pulp manufactured from soft wood.

4. A laminated board, the facing lies of which consist of wood pulpmanuf ctured from ground, cooked hard wood and the center plies of whichconsist of pulp manufactured from soft wood.

5. A laminated board, the facing plies of which include a layercomprising ground 20 cooked hard wood and another layer of pulpmanufactured from other material.

6. A laminated board, the facing plies of which include a layerconsisting of ground cooked hard wood and a layer formed of 25 pulpmanufactured from other material.

In witness whereof I have hereunto set my hand this 9th day of April,1923.

. HARRY S. LEWIS.

